One proposed structure of a power supply device is equipped with a chargeable and dischargeable battery (see, for example, Patent Document 1). The power supply device of this proposed structure sets an output limit as an electric power dischargeable power from the battery, based on the state of charge and the temperature of the battery, in order to prevent deterioration of the battery due to a decrease in state of charge of the battery or a temperature increase of the battery.    Patent Document 1: Japanese Patent Laid-Open No. H10-136502